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Understanding Acoustic Guitar Dimensions and Design

Understanding Acoustic Guitar Dimensions and Design

Putting a guitar together is a very complex job. It requires skill, patience and a lot of time.

This is why the best acoustic guitars are very expensive. Sure, you can have a guitar to call your own for less than $100, but you can bet your stiff and sore fingers that the purchase is going to end in disappointment.

Acoustic guitars come in different sizes and shapes. But even those that look identical can be different, because building a guitar requires exact measurements.

One guitar can differ from another by a matter of millimeters. If you want to understand acoustic guitars better, you must also have a grasp of the art and science behind their creation.

Here we discuss some of the considerations luthiers (guitar makers) take when they make acoustic guitars.

Dimensions and Measurement

When deciding on a guitar’s dimensions, a luthier thinks about the volume and tone output, plus the playability of the instrument. These dimensions cover the upper and lower bout, the depth of the body, the waist and the length of the entire instrument.

In order to establish the intonation, volume and playability, guitar makers focus on the lower bout width, which commonly ranges from 14” to 17”.

The Auditorium, the Grand Concert, the OM and the 000 guitars’ lower bouts measure between 14” and 15”. These guitars are usually the preference of recording artists.

The brightness of the sound of models in the 14” range is preferred by singer-songwriters and folk artists, while the boom of the bass of guitars in the 15” range is more favored by artists who do solos that require finger style playing.

Dreadnought guitars, which are in the 16” range, are widely used for bluegrass flatpicking. This is because dreadnoughts can play on the lower registers without distorting the sound, thanks to their heavy bass response.

Guitars that are in the 17” range are the jumbo guitars. They are most commonly used for acoustic blues – which require a powerful tone and a deep and heavy bass.

The Length of the Scale

This refers to the strings’ speaking length, which is also known as the distance from the saddle to the nut’s leading edge.

There is no need to go into the specifics of this; you just have to know that the shorter the distance or the scale length, the lower the tension there is on the string.

Blues players need lower tension or a short scale, because decreased tension allows the guitar player to easily bend the strings.

However, short scale is not advisable for guitar players that do not require a lot of bends, especially because fretted strings can cause the instrument to be out of tune.

On the other hand, increased tension is responsible for clearer and more focused tone projection. However, long scale can make fretting more difficult, especially for beginner guitar players.

The Spacing of the String

Spaces between the strings need to be carefully measured, in order for the guitar to sound right.

Spacing the strings is done through the nut. Experienced luthiers know that they should measure the spaces individually, taking into consideration the varying diameters of the strings (bass strings are thicker).

It must be noted that the spacing at the nut is different from the saddle spacing, due to the fact that most fingerboards have a tapered shape.

Good luthiers make sure that the tapering of the fingerboard, the width of the fret board and the spacing of the strings at the nut are based on the kind of sound the guitar player prefers.

The Radius of the Fingerboard

Is the fret board flat or curved? The radius of the fret board determines this.

Generally, classical guitars have flat fingerboards, while steel-stringed guitars have curved ones that range from 7.25” to 20”. The curvature of the fret board is not really dependent on anything, except the user’s preference.

The Profile of the Neck

The neck can make or break the feel of the guitar, and can greatly affect the comfort of the player, so luthiers pay great attention to the depth, taper and width of the neck. There are three common neck profiles:

  • The C Neck. This neck profile is smoother, more curved and fits easily in smaller hands.
  • The D Neck. This neck profile is thicker and fits larger hands better.
  • The V Neck. This is two flat edges put together to form a V, with the point where they meet touching the palm.

The ideal neck is a combination of all these profiles, falling in between – this ensures better grip and greater comfort for the player.

Fretwire Dimensions

Luthiers also make decisions regarding the height and width of the fretwire. These dimensions can affect the longevity of the guitar and ease of playing, especially for players who like doing fast licks.

The Neck Wood

It may seem thin, but the neck bears a lot of tension from the length of the scale and the gauge of the string. Therefore, the wood used for the neck must be strong. If this were the only consideration, then oak or maple could be used for the neck.

But strength is not the only consideration; luthiers are also looking for low weight. Oak is heavy, so it is not ideal. Maple, on the other hand, is not ideal because of its density.

The most commonly used type of wood is mahogany because of its strength and weight and its ability to cope with environmental changes. Other types include rosewood, walnut, sapele and cherry.

The Soundboard Wood

This is the focal point of the guitar, because this is the part that serves as the speaker. Therefore, the wood used must be resonant, as well as lightweight and flexible.

It must also have the proper thickness – which is also dependent on the kind of wood being used. The most common types of wood used for the soundboard include spruce, cedar and redwood, among others.

These are just some of the design and dimension considerations luthiers look at when making an acoustic guitar.

Next time you pick up your guitar, or buy a guitar, you will be able to understand more why the guitar sounds and feels the way it does.